John C. Sedbrook

Assistant Professor of Genetics

Postdoctoral Research: Carnegie Institution, Stanford University, Stanford, CA

Research Interests

Research Description

Instead of walking to sources of water, nutrients, and energy, plants must grow to them. Plants accomplish this by sensing a variety of environmental stimuli and integrating the ensueing physiological signals into an overall growth response. My laboratory studies how plants do this, focusing on the poorly understood molecular and genetic mechanisms underlying environmentally induced directional cell expansion.

We have identified a number of Arabidopsis cell expansion mutants by screening for plants whose roots grow abnormally down an inclined agar surface. Normally under this environment, Arabidopsis roots respond to gravity and touch stimulation by growing into the shape of a sinusoidal wave, in a process termed root waving.

Of the large number of root waving mutants that we have identified, a handful fall into a class characterized by roots that grow at an angle from the normal downward waving direction. The cloning and molecular characterization of these so-called sku mutants (stands for root skewing) is leading to new insights into how cells expand.

Representative Publications

Yuen, C. Y., Sedbrook, J. C., Perrin, R. M., Carroll, K. L., and Masson, P, H. (2005). Loss-of-function mutations of ROOT HAIR DEFECTIVE3 suppress root waving, skewing, and epidermal cell file rotation in Arabidopsis. Plant Physiol. 138: 701-714.

Gillmor, C. S., Lukowitz, W., Brininstool, G., Sedbrook, J. C., Hamann, T., Poindexter, P., and Somerville, C. (2005). Glycosylphosphatidylinositol-anchored proteins are required for cell wall synthesis and morphogenesis in Arabidopsis. Plant Cell. 2005 17: 1128-1140.

Sedbrook, J. C. (2004). MAPs in plant cells: delineating microtubule growth dynamics and organization. Cur. Opin. Plant Biol. 7: 632-640.

Sedbrook, J. C., Ehrhardt, D. W., Fisher, S. E., Scheible, W.-R., and Somerville, C. R. (2004). The Arabidopsis SKU6/SPR1 gene encodes a plus-end localized microtubule-interacting protein involved in directional cell expansion. Plant Cell 16: 1506-1520.

Boonsirichai, K., Sedbrook, J. C., Chen, R., Gilroy, S., and Masson, P. H. (2003). ARG1 is a peripheral membrane protein that modulates gravity-induced cytoplasmic alkalinization and lateral auxin transport in plant statocytes. Plant Cell. 15: 2612-2625.

Sedbrook, J. C., Carroll, K.L., Hung, K.F., Masson, P.H. and Somerville, C.R. (2002). The Arabidopsis SKU5 gene encodes an extracellular glycosyl phosphatidylinositol-anchored glycoprotein involved in directional root growth. Plant Cell 14: 1635-1648.

Sedbrook, J. C., Chen, R. J., and Masson, P. H. (1999). ARG1 (Altered Response to Gravity) encodes a novel DnaJ-like protein that potentially interacts with the cytoskeleton. Proc. Natl. Acad Sci. USA 96: 1140-1145.

Lynn, K., Fernandez, A., Aida, M., Sedbrook, J., Tasaka, M., Masson, P., and Barton, M. K. (1999). The PINHEAD/ZWILLE gene acts pleiotropically in Arabidopsis development and has overlapping functions with the ARGONAUTE1 gene. Development 126: 469-481.

Chen, R., Hilson, P., Sedbrook, J., Rosen, E., Caspar, T., and Masson, P. H. (1998). The Arabidopsis thaliana AGRAVITROPIC1 gene encodes a component of the polar-auxin-transport efflux carrier. Proc. Natl. Acad Sci. USA 95: 15112-15117.

Sedbrook, J. C., Kronebusch, P. J., Borisy, G. G., Trewavas, A. J., and Masson, P. H. (1996). Transgenic AEQUORIN reveals organ-specific cytosolic Ca2+ responses to anoxia in Arabidopsis thaliana seedlings. Plant Physiol. 111: 243-257.

Hirschie Johnson, C., Knight, M. R., Kondo, T., Masson, P. Sedbrook, J., Haley, A., and Trewavas, A. (1995) Circadian oscillations of cytosolic and chloroplastic free calcium in plants. Science 269: 1863-1865.

Extramural Funding

The National Institutes of Health (Academic Research Enhancement Award), 2003-2006. Roles of the SKU genes in directional cell expansion.

The National Science Foundation, 2005-2008. Regulation of cell expansion and microtubule function by SPR1.